3v4l.org

run code in 200+ PHP versions simultaneously
<?php foreach (['NULL', null, 0, false, ''] as $foo) { var_dump( $foo, is_null($foo) ); echo "\n\n"; }
based on kj6Bi
Output for 7.1.0 - 7.4.0
string(4) "NULL" bool(false) NULL bool(true) int(0) bool(false) bool(false) bool(false) string(0) "" bool(false)